a converging lens has a focal length of 250 millimetre calculate its power and Express it according to sign convention

Dear Student

given:- focal length= 250 mm. or 25 cm.

now since it is a convex lens, so focal length would be positive.

so power of lens= 100/f(cm)

P= 100/25

P= 4 D

so power of lens is + 4 D.

Regards